Reactivity of alkyl phosphonyl dichlorides for its esterification and dimerization of 5,5-diethyl-2-chloro-1,3,2-dioxaphosphorinane-2-oxide

Abstract

The alkyl phosphonyl dichlorides, R-$POCl_2$, (R ; isopropyl-, dichloromethyl-, tert-butyl) was prepared by aluminum chloride process, which had developed by A.M. Kinnear and E.A. Perren. Condensation reactions between these dichlorides and various alcohols were investigated and their reactivity was investigated. The best results were obtained when triethylamine was used as hydrochloric acid trapping agent in case of isopropyl- and dichloromethyl phosphonyl dichloride. But tert-butyl phosphonyl dichlorides required more strong condition, and several side reactions occurred. Among these, one was the formation of triethyl ammonium phosphonates. Large membered ring molecule containing phosphorous, which are believed as dimer of 5,5-diethyl-2-chloro-1,3,2-dioxaphosphorinane 2-oxide, was also isolated. The resulting compounds were characterized by means of instrumental analysis methods. The nuclear magnetic resonance spectra were very complicated because of strong spin coupling and long range coupling with phosphorous atom. Infrared spectra showed P=O stretching band remarkably in the region of 1300 to 1200 $cm^{-1}$. The mechanism of phosphonylation was also discussed.